Single-domain antigen-binding antibody fragments derived from llama antibodies

Abstract

A phage display library of variable heavy domain (V_HH or VH) fragments (sdAb fragments) derived from the antibody repertoire of a non-immunized llama is disclosed. The sdAb fragments of the library are characterized by the absence of cysteine residues in complementarity determining regions (CDRs) and a very low presence of residues of glutamic acid, arginine and glycine at positions 44, 45 and 47, respectively, of the VL interface of the variable heavy domain V_HH. The large size of the library (in the order of 10⁹) makes it a source of antigen-binding fragments having high affinity to almost any antigen of interest. The library is preferably generated using a modified fd-tet phage growing in plaques in the absence of a tetracycline.

Description

RELATED APPLICATIONS [0001] This application is a divisional of U.S. application Ser. No. 10 / 031,874, filed May 25, 2001, now pending, and claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional application Ser. No. 60 / 207,234, filed May 26, 2000, the disclosures of which are incorporated by reference herein.FIELD OF THE INVENTION [0002] The invention relates to antigen-binding proteins, in particular to antigen-binding fragments of antibodies derived from a naive library of llama antibodies and to a phage display library of such fragments. More particularly, the present invention relates to antigen-binding fragments of llama antibodies comprising at least a part of the variable heavy domain (VH or VHH) of antibodies derived from a naive library of llama antibodies and to a phage display library of such fragments. BACKGROUND OF THE INVENTION [0003] The immune system in vertebrates provides a defense mechanism against foreign intruders, such as foreign macromolecules or infec...

AI Technical Summary

Benefits of technology

[0016] The present invention has overcome the above-discussed prior art limitations by generating a large size (in the order of 109) phage display library of antibody fragments of a non-immunized llama, which fragments comprise at least a part of the variable heavy domain (VH or VHH domain) of llama antibodies. In a preferred embodiment, the fragments consist essentially of the variable heavy domain (VH or VHH of llama antibodies (sdAb fragments). This library possesses a number of unique features which distinguish it from similar libraries generated from other camelids. The large size of the library considerably increases the probability of isolating therefrom antigen-binding fragments having high affinity to almost any predetermined target (antigen) of interest. This has been demonstrated by isolating from the library fragments binding specifically to several preselected antigens as targets.

Problems solved by technology

Moreover, this approach has serious drawbacks because most of the pathogenic antigens cannot be injected into camelids, as this could endanger their lives.

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